The invention relates to a heat recovery boiler and more particularly to an improved heat recovery boiler utilized with a rotary combustor for burning municipal solid waste.
Performance data obtained at various municipal waste incinerators indicated pockets of high concentrations of CO in the heat recovery boilers down stream of the combustors. Periodical or sporadic high concentration of CO in the heat recovery boiler may be due to heterogeneous variations in the municipal solid waste feed, whereas constant pockets of high concentrations of CO in the heat recovery boiler can be attributed to poor mixing and localized deficiency of oxygen. High concentrations of CO have been found in regions above ash burn out steps, where residual carbon in the ash smolders. Another region of high concentrations of CO has been found to be immediately above the extended barrel of the rotary combustor where it protrudes into the heat recovery boiler. If not eliminated these pockets of high concentration of CO may result in higher than desired concentration of CO in the exhaust stack.
The O'Connor patent number 4,699,070 shows a protuberance on the back wall with air nozzles disposed below the necked down portion of the flue and not in the portion of the flue where the velocity and turbulence are the highest. The protuberance is symmetrical and the angular disposition of the upper portion thereof is such that ash would collect thereon.